Cruise control (CC) has become a standard feature on most modern vehicles. It is a feature that provides the functionality of autonomously regulating a vehicle's speed around a driver-defined target speed (i.e., speed control). Although cruise, control is a feature that is standard on most vehicles, many drivers are reluctant to use it or use it in only a limited number of scenarios due to worrying about driving at a constant preset speed in various and/or varying road conditions. Examples of such road conditions include, but are not limited to, snow covered roads, icy roads, rough roads, hilly, curved, cambered roads, and the like. Furthermore, a driver's style of driving and/or behavior while driving (e.g., cautious driver, normal driver, expert driver, reckless driver, impatient driver, etc.) can influence their willingness and likeliness to use cruise control.
Adaptive Cruise Control (ACC) is an enhanced version of cruise control. Adaptive cruise control switches from a speed control mode of operation (i.e., speed control functionality) to a distance control mode of operation (i.e., distance control functionality) when the Vehicle (i.e., the follow vehicle) approaches another vehicle in front of it (i.e., the leading vehicle) that is travelling in the same direction (e.g., in the same road lane). Examples of apparatuses that can be used for sensing the leading vehicle include, but are not limited to, a radar-type sensing apparatus, a laser-type sensing apparatus, a lidar-type sensing apparatus, a camera-type sensing apparatus or the like. In response to sensing the leading vehicle and/or determining that the vehicles are within a specified distance from each other, adaptive cruise control causes the follow-vehicle to maintain a preset distance behind the leading vehicle (i.e., distance control) regardless if the leading vehicle reduces speed or brakes (e.g., the following vehicle decelerates and/or coasts until the preset distance is achieved). The preset distance can be speed-dependent such that the distance is proportional to the speed of the leading vehicle. Once the leading vehicle is passed or is otherwise no longer in front of the follow vehicle (e.g., turns off of the road or moves to a different lane), adaptive cruise control causing the follow vehicle to accelerate back to the preset cruise control speed under the speed control mode of operation. In this manner, to reduce a driver's concerns relating to maintaining constant speed while following another car, adaptive cruise control provides the functionality of changing the driver's vehicle's speed to maintain a pre-set gap (i.e., distance) between the driver's vehicle and the leading vehicle. Collision mitigation by braking (CMbB), which can be an enhancement of cruise control and active cruise control, is a safety feature that warns a driver of a leading vehicle and automatically applies brakes if there is a high risk of collision with the leading vehicle.
ACC is one example of integrating speed control with on-demand distance control. However, there are many driving situations where speed control and distance control need to be either arbitrated or switched among each other to achieve a vehicle motion state that is acceptable to the driver. For example, besides CC and ACC, modern vehicles can also be equipped with safety features such as Electronic Stability Control (ESC), Roll Stability Control (RSC), Traction Control System (TCS), Anti-lock Brake System (ABS) and/or with convenience/comfort features such as Fuel Economy Minder (FEM), Driver Advisory System, Controllable Suspension System, and Controllable Steering System. Accordingly, providing speed control used in CC device and/or distance control used in ACC device in combination with capabilities of one or more of these other safety, convenience, and/or comfort features will enhance driver assistance functionality, which can improve safety of the vehicle and, at the same time, enhance driving convenience and/or fuel economy. Furthermore, such an enhanced implementation of CC and/or ACC can potentially enhance driver's acceptance and utilization of such driver assist features.